1. Field of the Invention
This invention relates to the use of 1,5-pentanedial as the active antimicrobial agent in disinfecting and/or preserving solutions for contact lenses.
2. Description of the Prior Art
This invention relates to disinfecting contact lenses, particularly soft contact lenses. When the term "soft contact lenses" is used herein, it is generally referring to those contact lenses which readily flex under small amounts of force and return to their original shape when released from that force. Typically, soft contact lenses are formulated from poly(hydroxyethyl methacrylate) which has been, in the preferred formulation, crosslinked with ethylene glycol dimethacrylate. For convenience, this polymer is generally known as PHEMA. Soft contact lenses are also made from silicone polymers typically crosslinked with dimethyl polysiloxane. As is known in the art, conventional hard lenses usually consist of poly(methylmethacrylate) crosslinked with ethylene glycol dimethacrylate.
Hard contact lenses do not absorb appreciable amounts of water as do some soft contact lenses and thus the use of harsher disinfecting and cleaning agents does not create a problem in the hard contact lenses cleaning area. However, many hard lens disinfecting and preserving solutions contain benzalkonium chloride or chlorobutanol which may render the treated lenses hydrophobic, may not be stable in solution or lack compatibility with certain types of hard lenses, e.g., high silicone content. As is generally known the users of soft contact lenses are warned against using solutions made for hard contact lenses since the materials in the solutions, as mentioned, may be absorbed or even concentrated by the soft contact lenses and may seriously damage the soft contact lenses or the eye of the user.
U.S. Pat. No. 3,016,328, R. E. Pepper et al, discloses dialdehyde alcoholic sporicidal compositions containing a saturated dialdehyde, e.g., glutaraldehyde, an alkanol and an alkalinating agent. Also disclosed are aqueous sporicidal compositions containing a dialdehyde (0.25 to 4%) and an alkalinating agent, the solution having a pH of 7.4 or more. Medical, surgical and optical applications are suggested.
U.S. Pat. No. 3,697,222, G. Sierra, discloses the use of an aqueous acid glutaraldehyde solution at temperatures above 45.degree. C. to sterilize an object. The sterilizing action is enhanced by the use of ultrasonic energy. Sterilization also may be achieved by using ultrasonic energy and aqueous alkaline glutaraldehyde solutions, the preferred temperature being 55.degree. to 65.degree. C. Sierra teaches the aqueous glutaraldehyde concentration can be up to 7.5% and preferably 1 to 2%.
U.S. Pat. No. 3,912,450 and U.S. Pat. No. 3,968,248, R. M. G. Boucher, disclose disinfecting or sterilizing medical items by contacting the item with a sporicidal composition containing 0.1 to 5 weight percent of glutaraldehyde and 0.01 to 1 weight percent of an ethoxylate type non-ionic surface active agent and at a temperature of at least 15.degree. C. Boucher discusses this development in some detail in an article (Amer. J. Hosp. Pharm. 31:546-547) published June 1974.
U.S. Pat. No. 3,968,250, R. M. G. Boucher, discloses disinfecting and sanitizing fowl eggs with an aqueous solution containing 0.1 to 5% of glutaraldehyde and 0.01 to 1 percent of an ethoxylate type non-ionic surface active agent.
U.S. Pat. No. 4,093,744, M. W. Winicov et al, discloses an aqueous composition containing 2 to 4 weight percent of glutaraldehyde and 0.1 to 10 weight percent of a surfactant with a pH of 6.7 to 7.3 to kill bacterial spores. This patent further discloses "Independent analyses of the sporicidal compositions disclosed in U.S. Pat. No. 3,016,328 to Pepper et al revealed that the 10 hour contact kill time was readily obtainable when using a fresh solution, but that the efficacy of the compositions markedly decreased upon standing for prolonged periods of up to about two weeks. Further, this reduction in effectiveness was found to be attributable to the diminution of glutaraldehyde, which lost a total of about 25% of its by the end of a two week period."
Contact Lenses by Robert H. Hales, Williams & Wilkins Co., Baltimore, MD (1978) at page 33 records the use of glutaraldehyde as a chemical disinfectant for contact lens solution. While starting glutaraldehyde is a highly active bacterial and sporicidal agent, he notes it is toxic and irritating, unstable and requires an alkaline condition. No other mention is made of this antimicrobial agent.